U.S. patent number 10,192,541 [Application Number 15/308,731] was granted by the patent office on 2019-01-29 for systems and methods for generating speech of multiple styles from text.
This patent grant is currently assigned to Nuance Communications, Inc.. The grantee listed for this patent is Nuance Communications, Inc.. Invention is credited to Corinne Bos-Plachez, Paolo Mairano, Sourav Nandy, Silvia Maria Antonella Quazza, Johan Wouters, Dong-Jian Yue.
United States Patent |
10,192,541 |
Mairano , et al. |
January 29, 2019 |
Systems and methods for generating speech of multiple styles from
text
Abstract
A text-to-speech (TTS) system includes components capable of
supporting the generation of speech output in any of multiple
styles, and may switch seamlessly from producing speech output in
one style to producing speech output in another style. For example,
a concatenative TTS system may include a speech base storing speech
units associated with multiple speech styles, and a linguistic
analysis component to generate a phonetic transcription specifying
speech output in any of multiple styles. Text input may include a
style indication associated with a particular segment of the input
text. The linguistic analysis component may invoke encoded rules
and/or components based upon the style indication, and generate a
phonetic transcription specifying a speech style, which may be
processed to generate output speech.
Inventors: |
Mairano; Paolo (San Carlo
Canavese, IT), Bos-Plachez; Corinne (Baisieux,
FR), Nandy; Sourav (Lucknow, IN), Wouters;
Johan (Cham, CH), Quazza; Silvia Maria Antonella
(Turin, IT), Yue; Dong-Jian (Shanghai,
CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Nuance Communications, Inc. |
Burlington |
MA |
US |
|
|
Assignee: |
Nuance Communications, Inc.
(Burlington, MA)
|
Family
ID: |
54765953 |
Appl.
No.: |
15/308,731 |
Filed: |
June 5, 2014 |
PCT
Filed: |
June 05, 2014 |
PCT No.: |
PCT/CN2014/079245 |
371(c)(1),(2),(4) Date: |
November 03, 2016 |
PCT
Pub. No.: |
WO2015/184615 |
PCT
Pub. Date: |
December 10, 2015 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20170186418 A1 |
Jun 29, 2017 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G10L
13/10 (20130101); G10L 13/06 (20130101); G10L
13/047 (20130101); G10L 13/08 (20130101); G10L
13/07 (20130101) |
Current International
Class: |
G10L
13/00 (20060101); G10L 13/10 (20130101); G10L
13/07 (20130101); G10L 15/26 (20060101); G10L
13/08 (20130101); G10L 13/047 (20130101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102005205 |
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Apr 2011 |
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CN |
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103546763 |
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Jan 2014 |
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CN |
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Other References
International Search Report for International Application No.
PCT/CN2014/079245 dated Mar. 4, 2015. cited by applicant.
|
Primary Examiner: Patel; Shreyans A
Attorney, Agent or Firm: Wolf, Greenfield & Sacks,
P.C.
Claims
What is claimed is:
1. A method for use in a text-to-speech system comprising a
computer-implemented linguistic analysis component operative to
generate a phonetic transcription based upon input text, a speech
base comprising speech unit recordings associated with a plurality
of styles of speech, and at least one computer-implemented speech
generation component operative to generate output speech from
stored speech unit recordings based at least in part on the
phonetic transcription, the method comprising acts of: (A)
receiving, by the linguistic analysis component, input text
produced by a text-producing application, wherein the text produced
by a text-producing application comprises a speech style indication
indicating a style of speech to be output by the text-to-speech
system for an associated segment of the input text; (B) generating,
by the linguistic analysis component, a phonetic transcription
based at least in part on the input text, the phonetic
transcription specifying a first style of speech of the plurality
of styles of speech to be output by the at least one speech
generation component for the segment of the input text; and (C)
generating, by the at least one speech generation component, output
speech based at least in part on the phonetic transcription
generated in the act (B), wherein the generating comprises the at
least one speech generation component selecting, from the speech
unit recordings in the speech base, speech unit recordings
associated with a second style of speech of the plurality of styles
of speech, the second style of speech being different than the
first style of speech, and concatenating the selected speech unit
recordings to generate output speech in the first style.
2. The method of claim 1, wherein the first style is a didactic
style, and the second style is a neutral style.
3. The method of claim 1, wherein the act (C) comprises the at
least one speech generation component slowing down an output speech
rate and/or inserting at least one pause in the output speech.
4. The method of claim 1, further comprising an act (D) of
generating output speech for another segment of the input text by
applying, to the other segment, a statistical model associated with
a style of speech specified in the phonetic transcription for the
other segment.
5. The method of claim 1, wherein the act (A) comprises receiving
input text comprising a plurality of segments each having an
associated speech style indication, at least one of the speech
style indications being different than at least one other of the
speech style indications, the act (B) comprises generating a
phonetic transcription specifying a style of speech to be output
for each one of the plurality of segments according to the speech
style indication associated with the one segment, and the act (C)
comprises generating output speech for each one of the plurality of
segments according to the speech style indication associated with
the one segment.
6. The method of claim 5, wherein the plurality of segments
constitute a single sentence.
7. The method of claim 1, wherein the act (B) comprises the
linguistic analysis component invoking one or more rules and/or
components specific to a style of speech indicated by the speech
style indication.
8. A text-to-speech system, comprising: at least one storage
facility storing a speech base comprising speech unit recordings
associated with a plurality of styles of speech; and at least one
computer processor programmed to; receive input text produced by a
text-producing application, wherein the text produced by a
text-producing application comprises a speech style indication
indicating a style of speech to be output by the text-to-speech
system for an associated segment of the input text; generate a
phonetic transcription based at least in part on the input text,
the phonetic transcription specifying a first style of speech of
the plurality of styles of speech to be output for the segment of
the input text; and generate output speech based at least in part
on the generated phonetic transcription, the generating comprising
selecting, from the speech unit recordings in the speech base,
speech unit recordings associated with a second style of speech of
the plurality of styles of speech, the second style of speech being
different than the first style of speech, and concatenating the
selected speech unit recordings to generate output speech in the
first style.
9. The text-to-speech system of claim 8, wherein the first style is
a didactic style, and the second style is a neutral style.
10. The text-to-speech system of claim 8, wherein the at least one
computer processor is programmed to generate the output speech by
slowing down an output speech rate and/or inserting at least one
pause in the output speech.
11. The text-to-speech system of claim 8, wherein the at least one
computer processor is programmed to generate output speech for
another segment of the input text by applying, to the other
segment, a statistical model associated with a style of speech
specified in the phonetic transcription for the other segment.
12. The text-to-speech system of claim 8, wherein the at least one
computer processor is programmed to: receive input text comprising
a plurality of segments each having an associated speech style
indication, at least one of the speech style indications being
different than at least one other of the speech style indications;
generate a phonetic transcription specifying a style of speech to
be output for each one of the plurality of segments according to
the speech style indication associated with the one segment; and
generate output speech for each one of the plurality of segments
according to the speech style indication associated with the one
segment.
13. The text-to-speech system of claim 12, wherein the plurality of
segments constitute a single sentence.
14. The text-to-speech system of claim 8, wherein the at least one
computer processor is programmed to generate the phonetic
transcription by invoking one or more rules and/or components
specific to a style of speech indicated by the speech style
indication in the input text.
15. At least one non-transitory computer-readable storage medium
having instructions encoded thereon which, when executed in a
computer system, cause the computer system to perform a method
comprising acts of: (A) receiving input text produced by a
text-producing application, wherein the text produced by a
text-producing application comprises a speech style indication
indicating a style of speech to be output by the text-to-speech
system for an associated segment of the input text; (B) generating
a phonetic transcription based at least in part on the input text,
the phonetic transcription specifying a first style of speech to be
output for the segment of the input text; and (C) generating output
speech based at least in part on the phonetic transcription
generated in the act (B), wherein the generating comprises
selecting, from speech unit recordings in a speech base, speech
unit recordings associated with a second style of speech that is
different than the first style of speech, and concatenating the
selected speech unit recordings to generate output speech in the
first style.
16. The at least one non-transitory computer-readable storage
medium of claim 15, wherein the act (A) comprises receiving input
text comprising a plurality of segments each having an associated
speech style indication, at least one of the speech style
indications being different than at least one other of the speech
style indications, the act (B) comprises generating a phonetic
transcription specifying a style of speech to be output for each
one of the plurality of segments according to the speech style
indication associated with the one segment, and the act (C)
comprises generating output speech for each one of the plurality of
segments according to the speech style indication associated with
the one segment.
Description
BACKGROUND
Text-to-speech (TTS) systems generate output speech based upon
input text. FIG. 1 depicts a representative conventional TTS system
100 which performs concatenative speech generation. In
representative system 100, input text 105 (e.g., received from a
user, an application, or one or more other entities) is processed
by linguistic analysis component (LAC) 110 to generate phonetic
transcription 115. Unit selection module 120 processes the phonetic
transcription generated by LAC 110 to select speech units from
speech base 125 that correspond to the sounds (e.g., phonemes) in
the phonetic transcription and concatenates those speech units to
generate speech output 130.
Conventional TTS systems may be capable of generating output speech
in different styles. A style of speech is defined mainly by the
tone, attitude and/or mood which the speech adopts toward a subject
to which it is directed. For example, a didactic speech style is
typically characterized by a slow, calm tone which an adult would
typically adopt in teaching a child, with pauses interspersed
between spoken words to enhance intelligibility. Other speech
styles which conventional TTS systems may generate include neutral,
joyful, sad and ironic speech styles.
A speech style is characterized to some extent by a combination of
underlying speech parameters (e.g., speech rate, volume, duration,
pitch height, pitch range, intonation, rhythm, the presence or
absence of pauses, etc.), and how those parameters vary over time,
both within words and across multiple words. However, while speech
in a first style may be characterized by a different range of
values for a specific parameter than speech in a second style
(e.g., speech in a joyful style may have a faster speech rate than
speech in a neutral style), simply modifying the speech in the
first style to exhibit the parameter values characteristic of the
second style does not result in speech in the second style being
produced (e.g., one cannot produce speech in a joyful style simply
speeding up speech in a neutral style).
Conventional concatenative TTS systems generate speech output in
more than one style by employing a different "voice" for each
style, with each "voice" having an associated style-specific
linguistic analysis component (LAC) and speech base. A
style-specific linguistic analysis component may include
programmatically implemented linguistic rules relating to a
particular speech style. A style-specific speech base may store
speech units generated from recordings of a speaker speaking in the
particular speech style, or derivations of such recordings (e.g.,
produced by applying filters, pitch modifications or other
post-processing).
A representative conventional concatenative TTS architecture 200
operative to generate output speech in neutral, joyful or didactic
styles is depicted in FIG. 2. Architecture 200 includes systems
200A, 200B and 200C, with system 200A being operative to generate
speech in a neutral style, 200B being operative to generate speech
in a joyful style, and 200C being operative to generate speech in a
didactic style. Each system includes an associated style-specific
linguistic analysis component (LAC) and speech base. Thus, system
200A includes neutral style-specific linguistic analysis component
(LAC) 210A and neutral style-specific speech base 225A. Similarly,
system 200B includes joyful style-specific linguistic analysis
component (LAC) 210B and joyful style-specific speech base 225B,
and system 200C includes didactic style-specific linguistic
analysis component (LAC) 210C and didactic style-specific speech
base 225C. Linguistic analysis components 210A, 210B, 210C process
respective input text 205A, 205B and 205C to generate phonetic
transcriptions 215A, 215B and 215C. The phonetic transcriptions are
processed by respective unit selection modules 220A, 220B, 220C to
generate speech output. That is, unit selection 220A processes
phonetic transcription 215A to select and concatenate speech units
from neutral style-specific speech base 225A to produce neutral
speech output 230A, unit selection 220B processes phonetic
transcription 215B to select and concatenate speech units from
joyful style-specific speech base 225B to produce joyful speech
output 230B, and unit selection 220C processes phonetic
transcription 215C to select and concatenate speech units from
didactic style-specific speech base 225C to produce didactic speech
output 230C.
SUMMARY
The inventors have appreciated that, in a conventional TTS system,
switching from generating speech output in one style to generating
speech output in another style requires changing the system's
"voice." That is, to switch from producing speech output in a first
style to producing speech output in a second style, a conventional
system must unload from memory a linguistic analysis component and
speech base specific to the first style, and load to memory a
linguistic analysis component and speech base associated with the
second style. Unloading and loading components and data from memory
not only represents an unnecessary expenditure of computational
resources, but also takes time. As such, a conventional TTS system
cannot switch seamlessly from producing speech output in one style
to producing output in another style.
In accordance with some embodiments of the invention, a TTS system
is capable of switching seamlessly from producing speech output in
one style to producing speech output in another style. In some
embodiments, one or more components of the TTS system are not
style-specific, but rather support producing speech output in any
of multiple styles. Thus, switching from generating speech output
in a first style to generating speech output in a second style does
not require unloading from memory a linguistic analysis component
and speech base specific to the first style and loading to memory a
linguistic analysis component and speech base associated with the
second style, as in conventional systems. Because the switch from
one output style to another is seamless, some embodiments of the
invention may be capable of generating, in a single sentence of
output, speech in a plurality of styles.
In some embodiments of the invention, a text-to-speech system
includes a linguistic analysis component operative to process one
or more style indications included in text input, with each style
indication being associated with a segment of the text input. A
style indication may, for example, comprise a tag (e.g., a markup
tag), and/or any other suitable form(s) of style indication. Based
on a style indication for a segment of text input, the linguistic
analysis component may invoke encoded rules and/or components
relating to the indicated style, and generate a phonetic
transcription which specifies a style of speech to be output for
the segment. As such, in some embodiments of the invention, a
linguistic analysis component may be dynamically configured at run
time, based upon speech style indications provided in text input,
to generate phonetic transcriptions for speech in any of various
styles. In embodiments of the invention which support concatenative
speech generation, a unit selection component may process the
phonetic transcription by selecting and concatenating speech units
stored in a speech base to generate speech output. In embodiments
of the invention which support speech generation based upon
statistical modeling techniques, a statistical model associated
with a style of speech specified in the phonetic transcription may
be applied to generate speech output.
Some embodiments of the invention are directed to a method for use
in a text-to-speech system comprising a linguistic analysis
component operative to generate a phonetic transcription based upon
input text, and at least one speech generation component operative
to generate output speech based at least in part on the phonetic
transcription. The method comprises acts of: (A) receiving, by the
linguistic analysis component, input text produced by a
text-producing application, wherein the text produced by a
text-producing application comprises a speech style indication
indicating a style of speech to be output by the text-to-speech
system for an associated segment of the input text; (B) generating,
by the linguistic analysis component, a phonetic transcription
based at least in part on the input text, the phonetic
transcription specifying a style of speech to be output by the at
least one speech generation component for the segment of the input
text according to the speech style indication; and (C) generating,
by the at least one speech generation component, output speech
based at least in part on the phonetic transcription generated in
the act (B).
Other embodiments of the invention are directed to a text-to-speech
system which comprises at least one computer processor programmed
to: receive input text produced by a text-producing application,
wherein the text produced by a text-producing application comprises
a speech style indication indicating a style of speech to be output
by the text-to-speech system for an associated segment of the input
text; generate a phonetic transcription based at least in part on
the input text, the phonetic transcription specifying a style of
speech to be output for the segment of the input text according to
the speech style indication; and generate output speech based at
least in part on the generated phonetic transcription.
Yet other embodiments of the invention are directed to at least one
non-transitory computer-readable storage medium having instructions
encoded thereon which, when executed in a computer system, cause
the computer system to perform a method. The method comprises acts
of: (A) receiving input text produced by a text-producing
application, wherein the text produced by a text-producing
application comprises a speech style indication indicating a style
of speech to be output by the text-to-speech system for an
associated segment of the input text; (B) generating a phonetic
transcription based at least in part on the input text, the
phonetic transcription specifying a style of speech to be output
for the segment of the input text according to the speech style
indication; and (C) generating output speech based at least in part
on the phonetic transcription generated in the act (B).
The foregoing is a non-limiting summary of certain aspects of the
present invention, some embodiments of which are defined by the
attached claims.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram depicting a conventional concatenative
TTS system;
FIG. 2 is a block diagram depicting a representative conventional
architecture for generating speech output in multiple styles;
FIG. 3 is a block diagram depicting a representative concatenative
TTS system configured to generate speech output in any of multiple
speech styles, in accordance with some embodiments of the
invention;
FIG. 4A is a flowchart depicting a conventional process whereby a
TTS system switches from producing speech output in one style to
producing speech output in another style;
FIG. 4B is a flowchart depicting a process whereby a TTS system
produces speech output in multiple styles without changing the
voice, in accordance with some embodiments of the invention;
FIG. 5 is a block diagram depicting a representative TTS system
configured to employ statistical modeling techniques to generate
speech output in any of multiple speech styles, in accordance with
some embodiments of the invention; and
FIG. 6 is a block diagram depicting a representative computer
system with which some embodiments of the invention may be
implemented.
DETAILED DESCRIPTION
Some embodiments of the invention are directed to a TTS system
capable of generating speech output in any of multiple styles, and
switching seamlessly from producing speech output in one style to
producing speech output in another style, without changing the
"voice" of the system. For example, some embodiments of the
invention are directed to a concatenative TTS system which includes
a speech base storing speech unit recordings associated with
multiple speech styles, and a linguistic analysis component
operative to generate a phonetic transcription specifying speech
output in any of multiple styles. Text input processed by the
linguistic analysis component may, for example, include at least
one style indication, with each style indication being associated
with a particular segment of the input text. The style indication
for a segment of input text may cause the linguistic analysis
component to invoke encoded rules and/or components relating to the
indicated style. The linguistic analysis component may generate a
phonetic transcription which specifies a style for speech to be
output for the segment. A unit selection component may process the
phonetic transcription by selecting and concatenating speech units
from the speech base so as to produce speech output for each
segment in the indicated style.
A concatenative TTS system implemented in accordance with these
embodiments may offer numerous advantages over conventional
concatenative TTS systems. In this respect, a concatenative TTS
system which includes a linguistic analysis component capable of
generating phonetic transcriptions which include multiple speech
styles and a speech base which stores speech unit recordings in
multiple speech styles may be capable of switching between
producing output speech in one style to producing speech output in
another style seamlessly, without changing the "voice" of the
system. As such, a concatenative TTS system implemented in
accordance with some embodiments of the invention may be capable of
producing speech output which includes multiple speech styles in a
single sentence, and may offer improved performance and reduced
latency as compared to conventional concatenative TTS systems.
These and other advantages are described in detail below.
FIG. 3 depicts a representative concatenative TTS system 300
implemented in accordance with some embodiments of the invention.
Components of representative system 300 include linguistic analysis
component 310, unit selection component 320 and speech base 325.
FIG. 3 also depicts various input to, and output produced by, those
components (shown as rectangles in FIG. 3). The components of,
input to and output produced by representative system 300 are
described below.
Linguistic analysis component 310 is operative to specify speech
output in any of various speech styles. In some embodiments of the
invention, linguistic analysis component 310 may be implemented via
software. However, embodiments of the invention are not limited to
such an implementation, as linguistic analysis component 310 may
alternatively be implemented via hardware, or a combination of
hardware and software.
Linguistic analysis component 310 processes input text 305, which
may be supplied by a user, by a text-producing application, by one
or more other entities, or any combination thereof. In some
embodiments of the invention, input text 305 includes one or more
style indications, with each style indication being associated with
a particular segment of the input. Any suitable style indication
may be provided, as embodiments of the invention are not limited in
this respect. For example, in some embodiments, a style indication
may comprise a tag (e.g., a markup tag) which precedes the
associated segment of text input. A representative sample of input
text is shown below. In the sample shown, four discrete segments of
input text have style indications of neutral, joyful, didactic and
neutral, respectively: \style=neutral\ This sentence will be
synthesized in neutral style. \style=joyful\ This sentence will be
synthesized in joyful style. \style=didactic\ This sentence will be
synthesized in didactic style. \style=neutral\ This sentence will
be synthesized in neutral style again.
It should be appreciated that, although in the sample above a
segment of input text is associated with a style indication which
immediately precedes it, embodiments of the invention are not
limited to such an implementation. In this respect, a style
indication may be associated with a segment of input text in any
suitable way, and need not be placed contiguous (e.g., immediately
preceding, immediately following, etc.) to the segment, as in the
sample shown above.
It should also be appreciated that although each style indication
in the sample above is associated with a segment of input text that
comprises a complete sentence, embodiments of the invention are not
limited to such an implementation. As described further below, in
some embodiments of the invention, a style indication may be
associated with a segment of input text comprising any suitable
number of words, including a single word.
In representative system 300, linguistic analysis component 310
processes a style indication for an associated segment of text
input by invoking rules and/or components that are specific to the
indicated style. These style-specific rules and/or components are
then used to generate a portion of phonetic transcription 315
corresponding to the segment. Using the example text input shown
above to illustrate, upon encountering the "\style=neutral\" tag at
the beginning of the text input, linguistic analysis component 310
may invoke rules and/or components specific to the neutral style,
and generate a portion of phonetic transcription 315 corresponding
to the text segment "This sentence will be synthesized in neutral
style." This portion of the phonetic transcription 315 may include
an indication that synthesized speech for this segment should be
output in a neutral style. In some embodiments, the indication may
comprise a markup tag, but this indication may be provided in any
other suitable fashion.
In some embodiments, after generating the portion of the phonetic
transcription corresponding to the text segment "This sentence will
be synthesized in neutral style," linguistic analysis component
encounters the "\style=joyful\" tag. As such, linguistic analysis
component 310 may invoke rules and/or components specific to the
joyful style, and generate a portion of phonetic transcription 315
corresponding to the text segment "This sentence will be
synthesized in joyful style." This portion of the phonetic
transcription may include an indication that synthesized speech for
this segment is to be output in a joyful style. Linguistic analysis
component 310 may continue to process segments of the input text
until the input text has been processed in its entirety.
It should be appreciated that although in the example above, text
segments and associated style indications are processed
sequentially in the order presented in the input text, embodiments
of the invention are not limited to such an implementation, and may
be processed in any suitable order. As one example, text segments
may be processed according to associated style indication, so that
all text segments having a first associated style indication (e.g.,
a "\style=neutral\" tag) may be processed first, and then all
segments having a second associated style indication (e.g., a
"\style=joyful\" tag) may be processed next, and so on until all
input text has been processed. Text segments and associated style
indications may be processed in any suitable fashion, as
embodiments of the invention are not limited in this respect.
Unit selection component 320 processes phonetic transcription 315
to generate output speech. Specifically, unit selection component
320 selects and concatenates speech units (e.g., demiphones,
diphone, triphones, and/or any other suitable speech unit(s))
stored in speech base 315 based upon specifications set forth in
phonetic transcription 315. Like linguistic analysis component 310,
unit selection component 320 may be implemented via software,
hardware, or a combination thereof.
In representative system 300, speech base 325 stores speech units
of multiple styles, with each speech unit having a particular style
indication (e.g., a tag, such as a markup tag, or any other
suitable indication). For example, demiphones from joyful
recordings may each have an associated joyful style indication,
demiphones from didactic recordings may each have an associated
didactic style indication, demiphones from neutral recordings may
each have an associated neutral style indication, and so on. Thus,
in processing a segment of phonetic transcription 315 having a
particular style indication (e.g., a tag indicating that speech
output should be produced in a neutral style), unit selection
component 320 may select speech units stored in speech base 325 of
the indicated style (e.g., speech units tagged as being neutral
style). Phonetic transcription 315 may also specify additional
linguistic characteristics (e.g., pitch, speech rate, and/or other
characteristics) which are employed by unit selection component 320
in generating speech output 330.
It should be appreciated that a concatenative TTS system capable of
generating speech output in any of multiple speech styles using
only a single linguistic analysis component and single speech base
offers numerous advantages over conventional concatenative TTS
systems. One advantage is the ability to switch from producing
speech output in one style to producing speech output in another
style without expending processing resources to switch voices. This
advantage is illustrated in the description of FIGS. 4A and 4B
below.
FIG. 4A depicts a process performed by a conventional concatenative
TTS system, and FIG. 4B depicts a process performed by a
concatenative TTS system implemented in accordance with some
embodiments of the invention. That is, representative process 400A,
shown in FIG. 4A, is performed by a conventional concatenative TTS
system, and representative process 400B, shown in FIG. 4B, is
performed by a concatenative TTS system implemented in accordance
with embodiments of the invention. Referring first to FIG. 4A, at
the start of representative process 400A, conventional TTS system
sets a neutral style for speech output by loading a neutral style
"voice" including a neutral style-specific linguistic analysis
component and neutral style-specific speech base to memory in act
405. Representative process 400A then proceeds to act 410, wherein
speech in a neutral style is generated as output.
Referring now to FIG. 4B, to set a neutral style for speech output,
a concatenative TTS system implemented in accordance with some
embodiments of the invention loads to memory a linguistic analysis
component and a speech base which are capable of supporting
multiple speech styles in act 450. The system generates
neutral-style speech output in act 455.
Referring again to FIG. 4A, to switch from generating speech output
in the neutral style to generating speech output in the joyful
style, the conventional concatenative TTS system unloads the
neutral style-specific linguistic analysis component and neutral
style-specific speech base from memory, and then loads a joyful
style-specific linguistic analysis component and joyful
style-specific speech base to memory in act 415. It should be
appreciated that style-specific linguistic analysis components and
speech bases typically consume significant storage resources, so
that unloading one style-specific linguistic analysis component and
speech base from memory and loading another style-specific
linguistic analysis component and speech base to memory expends
significant processing resources, and takes time. Conventional
concatenative TTS system then outputs generated speech in the
joyful style in act 420.
By contrast, a concatenative TTS system implemented in accordance
with embodiments of the invention switches from producing neutral
style speech output to producing joyful style speech output by the
linguistic analysis component invoking rules and/or components
associated with the joyful style in act 460. This switch is nearly
instantaneous, and results in minimal processing resources being
expended. The system then generates joyful style speech output in
act 465.
Referring again to FIG. 4A, to make another switch from producing
speech output in the joyful style to producing speech output in the
didactic style, the conventional concatenative TTS system repeats
the unload/load process described above in relation to act 415, by
unloading the joyful style-specific linguistic analysis component
and joyful style-specific speech base from memory, and loading a
didactic style-specific linguistic analysis component and didactic
style-specific speech base to memory in act 425. This switch, like
the switch described above, is time- and resource-intensive. The
conventional system then generates didactic style speech output in
the act 430, and process 400A then completes.
By contrast, a concatenative TTS system implemented in accordance
with embodiments of the invention switches from producing joyful
style speech output to producing didactic style speech output by
the linguistic analysis component invoking rules and/or components
associated with the didactic style in act 465. As described above,
this switch is seamless and results in comparatively little
processing resources being expended. The system then generates
didactic style output speech in the act 475, and process 400B then
completes.
It should be appreciated that although the example given above
relates to making only two switches in output speech styles (i.e.,
from neutral to joyful, and then from joyful to didactic), in some
implementations, numerous switches may be desirable and are
possible. Thus, it can be seen that by conserving processor cycles
and time with each switch, embodiments of the invention may
conserve significant resources (e.g., processing resources) for use
by other components, enable significantly faster performance,
and/or consume significantly less power, and these advantages will
compound over time.
Another advantage which a concatenative TTS system capable of
generating speech output in any of multiple speech styles using
only a single linguistic analysis component and single speech base
offers over conventional concatenative TTS systems is the ability
to switch between output speech styles seamlessly, without a
discernible delay or pause between output speech styles. In this
respect, the inventors have appreciated that some conventional
concatenative TTS systems may conserve processing resources by
loading multiple sets of style-specific components to memory at
once, so that unloading components specific to one style and
loading components specific to another style is not necessary. The
inventors have also appreciated, however, that even if sufficient
memory resources are available to store the multiple sets of
components, making a switch from producing speech output in a first
style to producing speech output in a second style conventionally
results in a pause between speech output in the first style and
speech output in the second style. By contrast, in accordance with
some embodiments of the invention, the transition between output
speech styles is seamless, without a pause being introduced between
output speech of different styles, as the linguistic analysis
component merely switches from invoking one set of rules specific
to the first style to invoking another set of rules specific to the
second style, and including the result of processing according to
the invoked rules in the phonetic transcription.
Some embodiments of the invention allow speech output to be
produced which includes speech of multiple styles in a single
sentence. For example, one or more words of the sentence may be
output in a first speech style, and one or more other words of the
same sentence may be output in a second speech style. For example,
consider the input text: \style=neutral\ These words will be
synthesized in neutral style, and \style=joyful\ these words will
be synthesized in joyful style.
This input text may be processed so that the words "These words
will be synthesized in neutral style, and" are output in neutral
style, and the words "these words will be synthesized in joyful
style" are output in joyful style. In some embodiments, no pause is
introduced between the output in the different styles. Conventional
concatenative TTS systems, even those which load multiple sets of
style-specific components to memory at once, are incapable of
producing speech output wherein a single sentence includes speech
of multiple styles.
In some conventional implementations, an application may be
configured to provide input to a TTS system, but may not be
configured to take advantage of all of the speech styles supported
by the TTS system. Using the example of FIG. 2 to illustrate, an
application may be configured to provide input text to
style-specific linguistic analysis components 210A and 210B to
produce neutral and joyful style speech output, but not to generate
didactic style speech. In such conventional implementations,
configuring the application to take advantage of an additional
speech style may necessitate significant modifications to the
application (e.g., to introduce API calls, etc.), testing of the
application, testing of the integration of the application and TTS
system, etc. By contrast, with some embodiments of the invention,
enabling an application to take advantage of an additional output
speech style may be accomplished by merely modifying the
application to insert an additional type of style indication (e.g.,
tag) into input text.
A concatenative TTS system implemented in accordance with some
embodiments of the invention offers a reduction in the storage
resources used to store linguistic analysis components as compared
to conventional concatenative TTS systems. In this respect, the
inventors have recognized that, in conventional TTS systems which
include multiple style-specific linguistic analysis components,
there is significant overlap between the program logic and data
employed by the different linguistic analysis components. By
consolidating the program logic and data into a single linguistic
analysis component, some embodiments of the invention may realize
significant storage savings. Additionally, the amount of effort
associated with maintaining and enhancing a single linguistic
analysis component over time may be significantly less than the
amount of effort associated with maintaining and enhancing multiple
separate linguistic analysis components as used by conventional TTS
systems.
Some embodiments of the invention may employ techniques to minimize
the amount of storage and memory resources used by a speech base
capable of supporting multiple output speech styles in a
concatenative TTS system. In some embodiments of the invention, a
TTS system may be configured to employ speech units associated with
one speech style to generate speech output in another speech style,
thereby conserving storage resources. For example, speech units
associated with a neutral output speech style may be processed at
run time so as to produce output speech in a hyper-articulated
(e.g., didactic) style, so that it is unnecessary to store separate
speech units to support the hyper-articulated style.
The run time processing which is performed to produce didactic
style speech output from neutral style speech units may take any of
numerous forms. For example, the phonetic transcription that is
generated by a linguistic analysis component may specify
post-processing to be performed on concatenated neutral style
speech units to generate didactic style speech output. In one
example, the phonetic transcription may specify a slower speech
rate (e.g., 80-85% of the speech rate normally used for neutral
style output speech) to produce didactic style speech output.
In another example, the phonetic transcription may specify that
pauses be interspersed in output speech at linguistically
appropriate junctures. In this respect, in neutral style speech,
pauses are typically inserted only in correspondence to
punctuation. Thus, the sentence "This evening we will have dinner
with our neighbors at 9 o'clock, so we'll meet in front of the
restaurant at 14 Main Street" may be output in neutral style as
"This evening we will have dinner with our neighbors at 9 o'clock
<pause> so we'll meet in front of the restaurant at 14 Main
Street." In accordance with some embodiments of the invention,
however, a phonetic transcription may specify that pauses be
introduced elsewhere in a sentence, so as to produce the enhanced
intelligibility which is characteristic of the didactic speech
style, even when using neutral style speech units. Using the
example sentence given above to illustrate, a phonetic
transcription may specify that pauses be inserted so that the
following speech is output: "This evening <pause> we will
have dinner with our neighbors <pause> at 9 o'clock
<pause> so we'll meet in front of the restaurant
<pause> at 14 Main Street." By inserting pauses at
linguistically appropriate junctures, embodiments of the invention
may employ neutral style speech units to produce speech output
having the qualities of didactic style speech, such as the slow,
calm style that an adult might use in attempting to explain a new
concept to a child.
Of course, the run time processing described above may be performed
to produce speech output in any suitable hyper-articulated style,
including styles other than the didactic style. Embodiments of the
invention are not limited in this respect.
A concatenative TTS system may be configured to insert pauses at
linguistically appropriate junctures to generate didactic style
speech output in any suitable fashion. In some embodiments of the
invention, a prosody model may be employed to insert pauses. A
prosody model may, for example, be produced through machine
learning techniques, hand-crafted rules, or a combination thereof.
For example, some embodiments of the invention may employ a
combination of machine learning techniques and hand-crafted rules
so as to benefit from the development pace, model naturalness and
adaptability characteristic of machine learning techniques, and
also the ability to fix bugs and tune the model which are
characteristic of hand-crafted rules.
Any suitable machine learning technique(s) may be employed. For
example, in some embodiments, the IGTree learning algorithm, which
is a memory-based learning technique, may be employed. Results
generated by the IGTree learning algorithm and any hand-crafted
rules may, for example, be represented in a tree data structure
which is processed by the linguistic analysis component in
generating a phonetic transcription for speech output. For example,
a speech style indication provided in input text which indicates
that speech output is to be produced in a didactic style may cause
the linguistic analysis component to traverse the tree data
structure and generate a phonetic transcription specifying that
didactic style speech is to be output for a segment of the input
text.
A prosody model which is employed to produce speech output in a
didactic style may be trained in any suitable fashion. In some
embodiments of the invention, a prosody model may be automatically
trained from a labeled corpus, which may be created, for example,
by manual labeling, extracting silence speech units from didactic
style recordings, pruning breaks from a training text which
includes weak prosodic breaks via rules, pruning breaks from a
training text which includes syntactic breaks via rules, and/or one
or more other techniques.
Although the illustrative embodiments described above relates to
generating a hyper-articulated style speech from neutral style
speech units, it should be appreciated that embodiments of the
invention are not limited to such an implementation, and that
speech output in any particular style may be generated from speech
units associated with any one or more other styles. Further, any
suitable technique may be used to generate speech output in one
style using speech units associated with one or more other styles.
For example, a variation of the prosody model described above which
is used to generate didactic style speech may be used to generate
speech output in one or more other styles. Any suitable
technique(s) may be employed.
The inventors have recognized that, in certain applications, it may
be less desirable to generate speech output in one particular style
from speech units associated with another particular style. For
example, it may not be feasible to generate didactic style speech
output using joyful style speech units. As such, in some
embodiments of the invention, information may be stored (e.g., in
the speech base) which represents a "cost" at which speech units
associated with one style may be used to generate speech output of
another specified style. For example, this information may specify
a relatively low "cost" associated with using a neutral style
speech unit to generate didactic style speech output, but a
relatively high "cost" associated with using a joyful style speech
unit to generate didactic style speech output. The information
representing a "cost" may be processed, for example, by a unit
selection component configured to minimize the associated "cost"
for concatenated speech units.
Some embodiments of the invention are not limited to generating
speech using concatenative speech generation. Any suitable speech
generation technique(s) may be employed. For example, some
embodiments of the invention may employ statistical modeling
techniques (e.g., Hidden Markov Model (HMM) techniques, and/or one
or more other statistical modeling techniques) to generate speech
output.
Typically, statistical modeling techniques (e.g., HMM techniques)
involve a training phase during which parameters of statistical
models are derived. For HMM techniques, the statistical models are
typically Gaussians, and the parameters typically represent means
and variances of Mel Cepstral Frequency Coefficients (MFCC)
associated with an HMM state. The statistical parameters are
clustered by means of a decision tree. In each node of the decision
tree a question is asked related to the phonetic and prosodic
context of the state. The question results in an optimal split of
the parameters.
FIG. 5 depicts components of a representative TTS system 500
configured to employ statistical modeling techniques in generating
speech output. The components of representative system 500 include
linguistic analysis component 510, HMM decision tree 520, model
base 525 and parametric synthesis component 530. FIG. 3 also
depicts various input to, and output produced by, those components.
The components of, input to and output produced by representative
system 500 are described below.
Representative system 500 is similar to representative system 300
(FIG. 3) in that linguistic analysis component 510, like linguistic
analysis component 310 (FIG. 3), is configured to specify speech
output in any of multiple styles. Linguistic analysis component 510
receives input text 505 from a user, text-producing application,
one or more other entities, or a combination thereof. Input text
505 includes one or more style indications (e.g., tags), with each
style indication being associated with a particular segment of the
text input. Linguistic analysis component 510 invokes rules and/or
components specific to each indicated style in generating a
phonetic transcription 515. However, rather than being used by a
unit selection component to select and concatenate speech units
stored in a speech base, the phonetic transcription 515 is used by
decision tree 520 to apply one of the models stored in model base
525 (in representative system 500, joyful, neutral and didactic
models) to generate speech output. Specifically, in some
embodiments of the invention, a style indication included in the
phonetic transcription 515 may be used to generate a question which
is inserted near the top nodes of a decision tree that is employed
to select the model that is used in generating speech output. A
model which is used to generate speech output in a particular style
may be developed and trained in any suitable fashion, such as by
employing known techniques.
In some embodiments of the invention, a TTS system may enable one
or more external components (e.g., applications) to determine the
output speech style(s) that the TTS system supports. For example,
in some embodiments, a TTS system may provide an API which an
external component may access (e.g., may query) to determine the
output speech style(s) that are supported by the system. Such an
API may, for example, enable the external component to query the
system's linguistic analysis component, speech base (if a speech
base is provided), model base (if a model base is provided), and/or
any other suitable component(s) to identify the output speech
style(s) which are supported.
It should be appreciated that although the foregoing description
relates to a TTS system capable of producing speech output in
neutral, joyful and didactic styles, in some implementations, a TTS
system may be configured to produce speech output in one or more
additional styles, or in multiple styles that do not include all
three of the neutral, joyful and didactic styles. A TTS system
implemented in accordance with embodiments of the invention may
support speech generation in any two or more suitable styles.
It should be appreciated from the foregoing that some embodiments
of the invention may be implemented using a computer system. A
representative computer system 600 that may be used to implement
some aspects of the present invention is shown in FIG. 6. The
computer system 600 may include one or more processors 610 and
computer-readable storage media (e.g., memory 620 and one or more
non-volatile storage media 630, which may be formed of any suitable
non-volatile data storage media). The processor 610 may control
writing data to and reading data from the memory 620 and the
non-volatile storage device 630 in any suitable manner, as the
aspects of the present invention described herein are not limited
in this respect. To perform any of the functionality described
herein, the processor 610 may execute one or more instructions
stored in one or more computer-readable storage media (e.g., the
memory 620), which may serve as non-transitory computer-readable
storage media storing instructions for execution by the processor
610.
The above-described embodiments of the invention may be implemented
in any of numerous ways. For example, the embodiments may be
implemented using hardware, software or a combination thereof. When
implemented in software, the software code can be executed on any
suitable processor or collection of processors, whether provided in
a single computer or distributed among multiple computers. It
should be appreciated that any component or collection of
components that perform the functions described above can be
generically considered as one or more controllers that control the
above-discussed functions. The one or more controllers can be
implemented in numerous ways, such as with dedicated hardware, or
with general purpose hardware (e.g., one or more processors) that
is programmed using microcode or software to perform the functions
recited above.
In this respect, it should be appreciated that one implementation
of the embodiments of the present invention comprises at least one
non-transitory computer-readable storage medium (e.g., a computer
memory, a floppy disk, a compact disk, a tape, etc.) encoded with a
computer program (i.e., a plurality of instructions), which, when
executed on a processor, performs the above-discussed functions of
the embodiments of the present invention. The computer-readable
storage medium can be transportable such that the program stored
thereon can be loaded onto any computer resource to implement the
aspects of the present invention discussed herein. In addition, it
should be appreciated that the reference to a computer program
which, when executed, performs the above-discussed functions, is
not limited to an application program running on a host computer.
Rather, the term computer program is used herein in a generic sense
to reference any type of computer code (e.g., software or
microcode) that can be employed to program a processor to implement
the above-discussed aspects of the present invention.
Various aspects of the present invention may be used alone, in
combination, or in a variety of arrangements not specifically
discussed in the embodiments described in the foregoing and are
therefore not limited in their application to the details and
arrangement of components set forth in the foregoing description or
illustrated in the drawings. For example, aspects described in one
embodiment may be combined in any manner with aspects described in
other embodiments.
Also, embodiments of the invention may be implemented as one or
more methods, of which an example has been provided. The acts
performed as part of the method(s) may be ordered in any suitable
way. Accordingly, embodiments may be constructed in which acts are
performed in an order different than illustrated, which may include
performing some acts simultaneously, even though shown as
sequential acts in illustrative embodiments.
Use of ordinal terms such as "first," "second," "third," etc., in
the claims to modify a claim element does not by itself connote any
priority, precedence, or order of one claim element over another or
the temporal order in which acts of a method are performed. Such
terms are used merely as labels to distinguish one claim element
having a certain name from another element having a same name (but
for use of the ordinal term).
The phraseology and terminology used herein is for the purpose of
description and should not be regarded as limiting. The use of
"including," "comprising," "having," "containing", "involving", and
variations thereof, is meant to encompass the items listed
thereafter and additional items.
Having described several embodiments of the invention in detail,
various modifications and improvements will readily occur to those
skilled in the art. Such modifications and improvements are
intended to be within the spirit and scope of the invention.
Accordingly, the foregoing description is by way of example only,
and is not intended as limiting. The invention is limited only as
defined by the following claims and the equivalents thereto.
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